This invention relates to methods of packaging a cleanness-requiring product and apparatus used for such clean packaging.
Products such as silicon wafers, magnetic disks and photomasks require a high level of cleanness. Products in biotechnologies, pharmaceutical products and medical devices must be kept in a sterilized condition. Thus, prior art methods of packaging such a product typically included the steps of washing and drying both surfaces of a film sheet inside a clean room and sealing edges of the sheet after a product to be packaged is enclosed therein.
If a product is wrapped inside only one layer of film, the outer surface of the package becomes contaminated with contaminants such as dust while, for example, it is transported and delivered to its user. If the film is of a conventional, non-peelable kind and such a package is opened inside a clean room, these contaminants remaining on its external surface are likely to contaminate the interior of the clean room, and the product, if it is taken out into this contaminated atmosphere, will itself become contaminated, although the opening of the package takes place inside the clean room. For this reason, a cleanness-requiring product is frequently packaged inside a double layer of film by wrapping it twice in a film or placed in two bags one inside the other.
The prior art methods described above are disadvantageous firstly because two separate bag-forming processes are required, and secondly because the film, which serves as the packaging material, must be washed and dried before it is formed into a bag, and this affects the productivity adversely. Since apparatus for washing and drying are additionally required, furthermore, the packaging machine becomes large as a whole, and the cost of installing and operating the machine also increases.